One question for others with Catalysts (I have 3 8C's). As has been discussed, these speakers typically emit a slight hissing sound which is totally inaudible when any significant sound is coming through them, but which one would nevertheless like to minimize. This can be done, of course, by turning down the output knob on the back of the speakers, and correspondingly turning up the output in the AVR, but this can go only so far.
But I've discovered another wrinkle that (for me anyway) greatly diminishes the hiss, and this is connect the short adapter cable (XLR-RCA) that Mark sent with the speakers directly to the speaker, and then use a RCA-RCA to go however long is necessary to the AVR (which is no more than ~ 6 ft for me). I had originally understood (or may have misunderstood) Mark to say that it was best to connect his short adapter cable to the AVR (RCA end to the AVR) and use a longer XLR-XLR cable from this to the speaker. In my case though, I get significantly less hiss (for the same output level) by connecting the short adapter cable to the speaker and using a RCA-RCA as the extension cable, i.e., the first procedure described here.
I wonder if others of you have observed similar behavior. ???